Galvanometer.



PATENTBD APR. 23, 1907.

J. BROIGH.

GALVANOMETER.

APPLICATION FILED JUNE 27. 1906.

2 SHEETS-SHEET 1.

Witnesses;

172M212 tor.-

' .zen of the United States, and a resident of JOSEPH BROIOH, OFBROOKLYN, NEW YORK. GALvANoMETEh.

I Specification of Letters Patent.

Application filed June 27, 1906. Serial No. 323.577-

To all whom it may concern.-

Be it'known that I, JosEPH BRo'IoH, a citi- Brooklyn, in the county ofKings and State of New York, have invented certain new and usefulImprovements in Galvanometers, of which the following is aspecification.

. This invention relates to improvements in galvanometers, andparticularly to a device for preventing injury to the delicate pivotedor suspended movable coil of a galvanometer when the instrument is notin use.

The principal feature of my invention is a device by means of which themovable coil of a galvanometer may be held in such a manher that it willbe immovable in the direction of its axis when not in use, the deviceemployed by me for this purpose being not only simple in constructionand capable of manufacture and application to electrical measuringinstruments at a low cost, but also so constructed as not to interferein any way with the operation of the movable parts of the instrument orimpair its accuracy as a measuring instrument.

In the drawings accompanying thisspecification and forming part of thepresent application, Figure 1 is a plan, partly in section and withparts removed, of an electrical measuring instrument containing amovable galvanometer coil to which is applied a device for arresting orholding the movable coil in fixed position when not in use. Fig. 2 is acentral vertical section of the main portion of said instrument, showingthe movable coil held in a fixed position out of actionby means of myimproved arresting device. Fi v3 is a similar view showing the movablecoffin its normal position with the arresting mentsapplied thereto.

device held out of action. Figs. 4 and 5 are details illustratingrespectively in elevation and in plan the main element of the arrestingFig. 6 is i a lon itudinal section,

hlar suspension type having myimprove- Similar characters designate likeparts in all the figures of the drawings.

My invention may be applied to an electr1cal measuring instrument orgalvano'meter of any ty e containing a movable coil, but is illustratein Figs; 1 to 5 inclusive as applied to an ammeter of a well known type,in which '2 indicates the usual field magnet, 3 a core of known type.

' strument is not in use.

eighth of an inch or less is ample for this purmagnetizable material,such as soft iron, in fixed relation with the pole pieces of the fieldmagnet 2, and 4 a movable coil also of a well- The core 3 may be securedto the pole-pieces of the field magnet 2 in any suitable manner, as forexample, by the setscrews 5 at opposite sides of the core, whichset-screws pass through the frame 6 fastened to the pole-pieces of thefield magnet. All of these parts are or may be of well known con,-struction.

At the opposite ends thereof the movable coil has insulating blocks,such as 7 and 8,

cemented thereto but placed outside of' the coils of wire wrapped aroundthe frame of the movable coil 4. In these insulating blocks 7 and 8 areinserted the usual pivot-pins 9 and 10 for supportin the movable coil inits bearings. These earings for the pivot-pins 9 and lOmay be of anysuitable type, provided at least one of them is capable of adjustmenttoward and from the other a sufficient distance to permit the ends ofthe pivots- 9 and 10 to clear their bearings when the in- A movement ofonepose. I prefer to obtain the desired ad ust.- ment in the type ofgalvanometer shown in Figs. 1 to 5 by formingone of the bearings,

Patented April 23,1907.

such as 11, in a screw, such as 12, having a relativelyvlarge head 13,the under side or cheek ofwhich is accurately faced, as is the cheek ofthe coacting part, such as the cappiece 14 in which sald screw isthreaded. This cap-piece 14is firmly secured to the frame 6 and istherefore also in fixed relation with the field magnet and its poles andalso with the core 3, t ese parts being so organized as to bepractically a unitary structure,- none of the parts of which whenassembled are moved relatively to the others. The cappiece 14 isvertically bored and threaded in alinement with'the axis of; thecore 3for the reception of the cap-screw 12 containing the bearing 11, and itwill be understood that Y when-said screw 12 is screwed down to thelimit of its movement, with the check of its head in engagement with.the cheek of the cap-piece 14, the upper bearing will be in its properadjusted position for coaction with the upper pivot 9 of the movablecoil 3. The

"lower pivot 10 may work in a bearing 15 in a short screw or removablebearing piece 16 .which when once placed in posltion is not mtended tobe afterward adjusted. When so placed in this proper position thelower'bear mg will coact with the pivot 10 in such a manner as tocooperate properly with the upper pivot and the upper adjustablebearing.

The normal positions of the parts when in action are illustrated in Fi3, in which it will be seen that the movab e coil which surrounds thecore 3 at a slight distance therefrom is free to move about itsaxis andis unrestrained in the direction of its axis except by the pivot-pins 9and 10 bearing against their bearing surfaces. In such position, thebearings are liable to be injured by any sudden shock which theinstrument may sustain. It has been found in practice that wheninstruments of this kind are not in use, and

particularly during shipment, the movable coil, unless positively heldso that it can not move in the direction of its axis, frequently injuresand spoils the hearings in which the pivot-pins 9 and 10 are seated whenthe instrument is roughly handled. The reason for this is that theweight of the movable coil is such as to cause the sharp points of thedelicate pivot-pins to dig into the bearings when the instrument isroughly jarred or dropped during shipment, or otherwise roughly handled.In order to prevent spoiling of the bearings by such jarring of themovable coil I provide means for holding the movable coil in a fixedposition with the ivots 9 andv 10 out of contact with their earingsduring shipment of the instru ment,or at any time when theinstrument isnot in use. In order to accomplish this result I provide meanspreferably carried by the core 3, for holding the movable coil in such amanner when the instrument is not in use that it will be impossible forsuch coil to move in the direction of its axis. A device suitable forthis purpose is a spring or springressed actuator adapted to force themovab e coil against and hold it in contact with a suitable stop'face.Preferably the movable coil which surrounds the core 3, and as beforestated, and as is well known, has a slight clear space around it betweenit and the core, is pressed into en agement with one end of the core andheld mly in that position when the instrument is not being used. Forthis purpose I have illustrated at 17 a pin carried by the core 3 andpressed by a spring 18 into engagement with the movable coil at theinner side thereof.

referably seated and'works in a central axial ore in the core 3, at theextreme end of which bore a spring 18 is normally under compression, butwhen released serves to force the pin 17 up and with it the movablecoil, until the inner side of the movable coil at its lower end comes incontact with the lower end of the core 3, as shown in Fig. 2.

At its upper end the pin 17 may have rigid therewith a disc 19. in orderthat the mov- This pin 17 is able coil may be pressed upward by the pinregardless of the angular position of the coil about its axis.

It will be clear from the foregoing that the spring-pressed pin and discjust described will operate to hold the movable coil out of action atall times unless such pin and disc are themselvesheld out of action.,Normally said pin and disc will be held out of action and the spring 18will be under compression: In order to control these parts I may makeuse of any suitable means for holding them out of action, they beingpreferably controlled by the screw 12, which will hold the pin 17 out ofaction or permit it to come into action according as said screw isadjusted to shift said bearing away from or into its operative position.has projecting therefrom at one side thereof a pin 20 which passesthrough a bore in the cap-piece 14, which bore is parallel with thescrew-threaded bore in which the screw 12 works. The u per end of thepin 20 rests against the un er side of the head 13 of the screw 12. Whenthe screw 12 is screwed down to its working position, as shown in Fig.3, the in 20, disc 19 and pin 17 will also permitted to move freelyabout its axis and will only be restrained in the direction of its axisby the engagement of the ends of its ivot-pins with their end bearings.When, liowever, the screw 12 is unscrewed, as shown in Fig. 2, and theupper bearing shifted away from its ivotin a suitable distance, whichshould a ways e the same and is fixed by a stop 21, and with it willmove the disc 19 and the pin 17, these three parts (shown separately inFig. 4) being forced upward by the spring 1 8 as the upper bearing isunscrewed and shifted away from the lower bearin When the parts reachthe positions s own in Fig. 2, the movable coil will be stopped againstthe under side of the core 3 and will be held positively in thatposition by the pressure of the spring 18 against the 1 pm and disc incontact with the inner side of the upper end of the movable coil. Inthis position both pivot-pins 9 and 10 will be clear of their endbearings, and no ordinary jar or shock will be suffic1ent.to cause sucha movement of the movable coil in the direc-' Here the disc 19 be forcedown, and the movable coil will be tion of its axis as to force eitherpivot-pin into engagement with its bearing. Thus by simply unscrewingthe upper hearing when the instrument is not in use or is to be ship edto a distance, injuryto the pivots or bearlngs of the instrument will bepositively prevented. i

In Fi 6 I have shown my improved arresting viceapplied to a alvanorneterof the filar'suspenslon type. 1 of the parts of this instrument exceptthe arresting device are of well-known constructionthe movable coil 4,core 3, the mirror 21 and its sup- ISO rounds the core 3 at a slightdistance therefrom in the same manner as shown in Fig. 2, and the coreis held rigidly in place in the frame 29 by screws 5.

The arresting device used in connection with the movable coil of thisgalvanometer is in most respects identical in construction with thatillustrated in Figs. 1 to 5. It com- I prises apin 17 working in anaxial bore in the 1 means employed,

core 3 and normally pressed upward by a coiled spring 18 in the lowerend of said bore. At its upper end the spring-pressed pin 17 is attachedto a disc 19 whichpresses against the inner side of the upper end of themovable coil and forces. the movable coil upward.

when the spring 18 is released, in'the same manner that this action isaccomplished in the construction shown in Fi s. 1 to 5. The owever, orholding the "arresting device out of action is somewhat different fromthat illustrated in the main views, and this is due principally to the'difference in the two types of instruments. A long rod reduced indiameter at its lower end and passing through an opening in one side ofthe disc 19 andguidd at its lowerend in a bore 31 at one side of thecore 3, is here shown as the means for forcing the disc 19 and the pin17 down when the instrument is in'use. At its upper end the rod 30 isalso guided in a longitudinal bore at one edge of an externally threadedcollar 32, on which works a knurled adjusting-cap or nut 33.v

' This threaded cap 33 and the upper end of the'rod 30 are so placedthat the upper end of the rod is inposition to be forced down by theinner side of the head of the cap. When so forced down by the screwingdown'of said cap, into contact with the wide annular stopface or cheek34 of the collar 32, the arrestin device will be held-out of action bythe rod '30, and the instrument will be in its operative position. Whenthe cap is unscrewed, as

shown in Fig. 6, the spring 18 will force the parts to the positionshown in said fi ure, and the movable coil will be held firm y incontact with the under sideof the core 3, in which position it will beout of action and there will be no strain on the filar suspension 23. Inthis instrument, as in that shown in the main views, the arrestingdeviceand the means for holding it out of action are so constructed andso or anized with respect to the other parts that the accuracy of theinstru ment as a means for effecting delicate elec- I tricalmeasurements is not in any way im- 6 5 l paired.

What I claim is: v

1. In a galvanometer, the combination with a movable cdil having pivotsat its opposite ends, of end bearings for said pivots one of which ismovable relatively 'to the other and the other of which is fixed in allpositions of the pivots, and means for holding the pivots of saidmovable coil out of contact with said end bearings.

'2. In a galvanometer, the. combination with a movable coilhavi'ng'pivots secured .to

its opposite ends in the line of its axis, end bearings for said pivotsone of which bearings is movable relatively to the other and embodiesstops for locating it in two extreme positions, and means for holdingsaid movable coil in fixed position with its pivots out of contact withsaid end bearings.

3. In a galvanometer, the combination with, a field magnet and a core infixed'relation with each other, of a movable coil having pivots at itsopposite ends, end bearings for said pivots one of which is adjustablerelatively to the other,and means carried by the core for holding saidmovable coil in a fixed position in contact with one end of the core andwith its pivots out of contact with said end bearings.

4. In a galvanometer, the combination with a movable coil having pivotsat its opposite ends, of end bearings for said pivots one of-which isembodied in a screw-threadedmember adjustable relatively to the otherbearing in the direction of \the axis of the bearing, and meanscontrolled by said screwthreaded member for holding the pivots of saidmovable coil out'of contact with said end bearin s when the end bearingsare ad justed fart er apart. than the distance between said pivots.

.5. In a galvanometer, the combination 2 with afield magnet and a corein fixed relation with each other, of a movable coil having pivots atits opposite ends, end bearings for said pivots one of which is embodiedin a screw-threaded member adjustable relatively to the'other bearing inthe direction of the axis of the bearing, and a spring-pressed arrestingdevice carried by said core for holding said movable coil in afixed/position in the direction of the axis of the core, and normallyheld out of action by said screwthreaded'memberwhen the end bearings areadjusted farther apart than the distance between the pivots. p

6. In a galvanometer, the combination with a field magnet and a core infixed relation with each other, of a movable coil means for sup ortingsaid movable coil, an means carried by said core for preventing movementof said movablecoilin the direction of the axis of said core.

7. Ina galvanometer, the combination with with each other, of a movablecoil, means for sup orting said movable coil, and means carrie by saidcoil for holding said movable coil in a fixed position in contact withone end of the core.

8. In a galvanometer, the combination with a field magnet and a core infixed relation with each; other, of a movable coil, means for supportingsaid movable coil, and spring-actuated means carried by said core forholding said movable coil in a fixed position in contact with one end ofthe core.

9. In a galvanometer, the combination with a field magnet and a core infixed relation with each other, of a movable coil sur-' rounding andnormally clear of said core and shiftable into contact with one end ofthe core, means for supporting said movable coil,

and means carried by said core and in engagement with one end of themovable coil or holding said movable coil in contact with one end of thecore.

10. In a galvanometer, the combination with a field magnet and a core infixed relation with each other, of a movable coil surrounding andnormally clear of said core, means for supporting said movable coil, anda spiing-pressed pin working in said core and in engagement with one endofthe movable coil for holding said movable coil in contact with theopposite end of the core.

11: In a galvanometer, the combination with a field magnet and with anaxially bored core in fixed relation with each other, of a movable coilsurrounding and normally clear of said core, means for supporting saidmovable coil, and a spring-pressed'pin-working in said bore in the coreand having a disc head in engagement with'one end of the movable coilforholdingsaid movable coil'in contact with the opposite end of the core inany angular position of said coil.

' 12. In a galvanometer, the combination with a field magnet and a corein fixed relation with each other, 'ofa movable coil,

means for supporting said movable coil, .an'

arresting device carried-by said core for reventlng movementof'said-movable coi 1n the direction of the axis of sa1d .core,-and

means for'holding said anesting device .out 5c of action.

13. In a galvanometer, the combination with a field magnet and a core infixed relationwith each other, of a movable coil shiftable' into-contactwith one-end of the of June, A. D. 1906.- 1

core, means for supporting said movable coil, an arresting devicecarried by said core for holding said movable coil in a fixed positionin contact with' one end of the core, and means for holding saidarresting device out of action.

14. In a galvanometer, the combination with a field magnet and a core infixed rela- 1 tion with each other, of a movable coil surrounding andnormally clear of said core, means for supporting said movable coil, anarresting device carried by said core and in engagement with one end ofthe movable coil -for holding said movable coil incontact with one endof the core, and means for holding said arresting device out of action.

16. In a galvanometer, the combinationwith a field magnet and a core infixed relation with each other, of a movable coil, means for supportingsaid movablecoil, an arresting device carried by said core for reventingmovement of said 'movable coi in thedirectionof the axis {of said core,and

means including a screw-threaded adjusting device for holding saidarresting device out of action.

1 7. In a galvanometer, the combination with a field magnet and a corein fixed relation with each other, of a movable coil surrounding andnormally clearof said core, means for en porting .said movable coil, aspring-pressed pin working in said core and in engagement'with one endof the movable coil for holdin said movable coil in a fixed position inthe direction of the axis of said core, and means including ascrew-threaded adjusting device for. holding said arresting device outof action.

Signed at New York; in the county of New York, and State of New York,this 22nd day JOSEPH BROICH.

Witnesses: I EDGAR A. FELLows,

ROBERT CHAMPION.

